Improvement in duplex telegraphs



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Duplex Telegraphs.`

- Patented Feb. 17,1874.

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MMX m wnfe Unrrnn STATES PATENT OFFICE,

yEORGES DINFREVILLE, OF NEW YORK, N. Y., ASSIGNOR OF ONE-FOURTH HISRIGHT TO WILLIAM N. ARMSTRONG, OF SAME PLACE.

IMPROVEMENT IN DUPLEX TELEGRAPHS.

Specification forming part of Letters Patent No. 147,487, dated February17, 1874; application filed April 25, 1873.

To all whom it may concern: l

Be it known that I, GEORGES DINFREVILLE, residing at the city of NewYork, in the county and State of New York, have invented a new andsimple Method of Adapting Duplex Transmission to an ordinary TelegraphicLine, of which the following is a specification:

The object of this invention is to obtain a simple method of sendingmessages simultaneously, over the same wire, in 'opposite directions,either between terminal, or terminal and way, or wayv and way, stations.It has, for a further object, the sending of messages, as above setforth, with the least possible change of instruments and dispositionsalready in use; and for this purpose, and for illustration, the Morsesystem is herein chosen.

My invention requires the following arrangements First, in opposingtoeach oth er, thro ugh a telegraphic line, at its extremities, thesimilar poles of the terminal batteries, so that they have a commoncircuit, and neutralize each other, second, in using a singlecontact-key at each station in working the line for duplex transmission.The anvil of this key connects with the ground, while a wire from itslever `is in junction with a proper point in the wire of the helices ofthe main electro-magnet, the purpose of which I will describe hereafter;third, the exposing of one or more layers or parts of the helices of onespool of the main electro-magnet, so that direct contact can be made, atany desirable point in the helices, with the wire from the lever of thekey; fourth, a shunt-circuit of variable and proper resistance, oneextremity of which is attached to the wire connecting the key with thehelices above described, the other extremity being connected, whenrequired, with one or the other end of the wire going out of theelectro-magnet, as explained hereafter.

By way of explanation, l state that, in a common circuit, when the polesof two batteries are opposed, their effects are neutralized; but, ifawire connects the common circuit with the ground, two distinct circuitsare at once made. Also, if one spool of a common electromagnet betraversed by an electric current, and the other spool be traversed by acurrent My invention consists in the combination and use of theabove-mentioned opposin g batteries, electro magnets, singlecontactkeys, with shunt-circuit, if necessary, so that thedepressingofthekeyatthesending-stationdivides the common circuit of thebatteries hereinbcfore described into two independent circuitsone of thedistant and receiving station, through the line and sending-station, andthe other a short circuit of the battery at the sending-station, theformer recording signals at the receiving-station, and both circuitsneutralizing each others eects in the sending-station, so that itsarmature is not affected; and, also, by depressing simultaneously thekeys at terminal stations, two distinct local and independent circuitsare made at each station, and each station records only the signal oftheother.

The circuit-reversers are here used in order to show how my system canbe used with the common Morse plan, and the single transmitting andordinary method used, by simply moving the circuit-reverser, andconnecting the line and batteries in the usual way.

My system, when used alone on Morses plan, would connect, through wiree, the electro-magnet and battery-pole B, dispensingwith X a b el, andnegative pole A would go directly to ground.

In the accompanying drawing, Fi gurel represents a plan view ot' thesystem, showing the arrangement for a line of three stations-twoterminal and one way--all in the same circuit. The disposition is thesame if more stations are used. Fig. 2 is a sectional view of thestations. Fig. 3 is a detail and end view of one coil of the mainelectro-magnet.

Similar letters of reference indicate corresponding parts.

The letter A represents the negative, and B the positive, pole of themain battery at terminal station O. The other terminal station, D, hasthe poles of its main battery represented by E for the negative, and Ffor the positive, pole. G is a way-station wit-hout any main battery.The poles of the batteries are connected with the arms ot' thecireuit-rcversers X and X2.

The drawing shows the line ready for duplex transmission. The circuit ofthe battery at station C as follows: Fro1n the positive pole B througharm a of circuit-reverser X, conductor b, anvil of common key R, (usedin single transmissiom) circuit-closer d of the key lt, conductor c,helices ot' the electro-magnet lI, through line-Wire I, and, it' theeut-out g is open, as shown, at waystation G, through electro-magnetJand circuitcloserj, (of the common key for single transmission,)conductor Z, again line l', helices otl electro-magnet at terminalstation l), conductor c2, circuit-closer d2, conductor b2, and conductorc2 of circuit-closer X2, which is attached to the screw-post of thepositive pole F, through battery at l), grcuiul-wire N, groundconductorN2, and other arm of circuit-reverser X, to negative pole A. Also,circuit from battery at station D is from positive pole F through a2 b2d2 c2, lnaguet L, line l, and way-station G, n'iagnet H, wire c d b, arma ot' circuit-reverser X, to positive pole B, through battery at c,other arm ot circuit-reverser X, conductor N2, to ground, and N tonegative pole E.

lt will be noticed in the drawing that the Morse key, withcircuit-closer, is shown in direct circuit in all the stations, so that,by merely changing the position ot' the circuitreverser of eitherterminal station, the line can be worked on the closed-circuit systemtor simple transmission, as now in use, the

relay-armatures being attracted when line .is not worked.

Fig. l shows at station (il a rheostat, O, in the shunt-circuit l,connecting the battery through keys lt and M2 around the magnet H, thearm m being used to bring into circuit a greater or less amount ot' theresista-nee O. Similar dispositions are made at the other stations. Atthe way-stations movable arm ot' the rheostat can be brought in contactwith one or the other extremity ot' the electro-magnet, as may berequired, through a eommutntor or switch attached to the arm. ln theposition as shown in the drawing, with. the batteries opposed and thekey at rest, no current llows in theline sufficient toovercome thesprings ofthe armatures, because, the circuit ot' both batteries beingalways closed,and the batteries being connected to the line so as tooppose each other, the currents become opposed to each other andneutralize the et'tect in the ing, ot' the electroanagnet ll', runningover a part of its helices, but leaving it where wire h2 is attached toit, through h2, key M2, part of conductor N2, and returning throughbranch Vof circuit-reverser X to the negative pole of battery. The othercurrent, from positive pole F at station D, being no longer opposed bycurrent from B at station C, passes through conductors a2 b2,circuit-closer d2, conductor c2, helices of electro-magnet L,magnetizing its cores, attracting its armature, recording signal of M2,through line I, magnet at waystations, recording same signal byattracting armatures, then to and through a part of electro-magnet atstation C to the junction of wire h2 with helices 5 thence throughwirch2, through 1 key M2, conductor N2 to the ground, back to ,1 negativepole E of battery at D, through part of N, and circuit-reverser X2.A

It will be noticed tha-t the current from B, working in local circuit,and current trom F use the wire h2, key M2, and part of conductor N2, incommon, from junction with the helices as far as the circuit-reverser X.The key M2 serves to conduct two currents.

Thile all the electro-magnets ot' the line have their armaturesattracted bythe current from lf), the electro-magnet Il at C, thesending-station, docs not attract its armature, for it has been dividedby wire h2 into two parts, which are now traveled by opposite currentsof difterent intensities. Each current tends to produce a magneticpolarity different from that ot' the other. lf the two parts of thehelices are so dividedA that the polarity which the strongest current,coming from the now local battery, tends to produce in goin g throughthe shortest part, nearly counterbalances or neutralizes the polaritywhich the weaker cnrrent, coming from the distant battery, tends toproduce in goin through the long'er part, and in opposite direction, noappreciable magnetization will take place in the cores of the yelectro-magnet, and the armature of II will not be attracted. Thus oneimportant condition ot' duplex telegraphy is secured.

'lhe dividing ot' the helices into two parts, so that the current in onepart shall neutralize properly t-he opposing current in the other part,is made by connecting the wire h2 to the exposed layers of theelectro-magnet at a point which the workin g ot' the line willdetermine. The proper connection made when, on depressing the key at anystation, its own armature is not att'ected, the other keys being atrest. Il" the key M at station l) is also depressed alone, the resultsare the same. lts armature is not at't'ected, but the armature ot'receiving-station is yat work.

1t thus l. tppears that by this disposition of the line and instruments,one key alone being depressed, the sending-station records its signal atthe receiving-station by receiving instead ot' sending a current, andallowing the current of the receiving-station its full force inrecording.

I have 'shown `the working' of the current when one key only-forinstance, M2-fis depressed. The duplex transmission will now be shown.If, while the key M2 is depressed, as above described, working thedistant stations, with its own at rest, the'key M at station D be nowdepressed, the current from positive pole F, at D ceases to pass throughthe line to C, because a short circuit is insta-ntly established. Thecurrent runs from positive pole F through a2 cl2 e2, through part ofmagnet L, back through wire 7L and N, to negative pole. As this current,moving on a short circuit, no longer runs along wire I to magnet H, theneutralization existing at H when M2 was alone depressed is destroyed,and its armature is at once attracted through the magnetization of localcurrent at (i, made by depressed key M2.

The currents of both batteries move in local circuits, because they meetthe least resistance in that way; their circuit is not broken throughthe line. The very slight escape of electricity in H and L to the line,from the local circuits, still oppose each other. The armature at D,which was attracted by the depressed key M2, still remains depressed,because the current from F still runs through a part of magnet L, andwith increased power, because it is on a short circuit. Stations C and Dare now in the same condition. It, now, key M be raised, the conditionof the current .and working is again the same as when M2 alone worked.The current from pole F again runs over line to H, neutralizes currentsfrom B, and armature of H goes back, while armature at L remainsattracted, as before, by the working of key M2. Thus the working of thearmature at each terminal station is dependent upon and controlled byworking of the key at opposite terminal station. Although waystation Ghas no main battery, it sends and receives messages in the same way. Ifthe key Pis depressed, the two currents from C and D cease to opposeeach other, and go to the ground in common through key P and conductor2, back to their respective negative poles. For it is well known that iftwo batteries are opposed to each other in a line, a ground-wire at anypoint of. the line will divide this line in two distinct circuits, eachof which will operate without interfering with the other. The armatureof II and of other way-stations, if any, are attracted by current frompositive pole B, going to G; and armatures at D and at otherway-stations, if any, are attracted by current from positive pole F,going to G. The opposite currents, meeting in the electro-magnet at G,neutralize each other, so its own n'icssagc is not recorded. Theway-stations do.not require a main battery. Station G does not require amain battery to transmit to or receive from C. It uses the main batteryat D for its local neutralization, exactly as D uses it, only it is at adistance. Also, G will use the main battery of C for its localneutralization when it is signaling with D; and Gr, in duplextransmission with D, will operate exactly as if was station C. This isan important part of my invention.

Thus any two stations, either terminal or way, or way and way, canperform duplex transmission. As above described, the wire h1 isconnected with a point in the helices of of current from B at e, untilthe neutralization is as complete as possible. The small rheostat inthis shunt serves to regulate its resistance according to the changeswhich may occurin'different parts of the circuit. This shunt itself isnot new 5 but I believe it to be new to use it, as I do, in securing aneutralization of currents in the electro-magnet by drawing otf anexcess of electricity.

I believe that opposing currents of batteries of the same line-circuitis not new. I believe that a key with a ground-wire is not new; but Ibelieve to be new, and I claim as my invention, and desire to secure byLetters Patentl. The method of duplex telegraphin g, substantially asdescribed, by localizing or shortcircuiting the main battery at thesending-stai tion, thereby preservnig the magnetic equilibrium in theslgnahng-instrument of that station, and allowing the battery of therecein'ng-station to there exert its full force in recording orindicating signals, substantially as herein described.

2. In combination with a normally-closed telegraphic line having mainbatteries, one at each terminal, connected to the line in opposition toeach other, open-circuit single contact-keys M M2 and branch circuits NN2, connected to the relay-magnets at a suitable point, the closing ofthe said keys short-circuiting or localizing the battery ofthesending-station through the proper `proportion of the coils of therelay, substantially as set forth.

3. In combination with a relay-magnet having its layers exposed forconnection to key, and for approximate adjustment, as described, theshunt-circuit Maud rheostat c, substantially as and for the purposes set forth.

4. In combination with the normally-closed line, having the branchcircuits 7L h2 and opencircuit single contact-keys, and opposedbatteries, as described, the battery-reversers and closed-circuit keys,substantially as set forth.

5.- The combination, at an intermediate or Way station, With the mainline of a duplex telegraph, ofthe open-circuit keyP and branch' asdescribed.

circuit i, connected to the relay between the terminals, the depressing`of the key closing independent circuits for both terminal batteries,giving signals to both sides of the Waystation in single transmission,or forming a duplex line with one terminal, substantially GEORGESDINFREVILLE. Witnesses W. N. ARMSTRONG,

WM. R. LEARN.

